Studies are to be carried out, mostly in vitro, to characterize complicated cellular reactions which lead to inactivation of repressor molecules. These will be based on the biochemical assay procedure which we have recently established. Using permeable and complete in vitro systems, attempts will be made to isolate and identify cellular components which are involved in prophage induction and in genetic recombination in E. coli. BIBLIOGRAPHIC REFERENCES: Smith, C.L. and M. Oishi (1976). The Molecular Mechanism of Virus Induction. I. A Procedure for the Biochemical Assay of Prophage Induction. Molec. Gen. Genet. 148: 131-138. Oishi, M. and R. Irbe. Circular Chromosomes and Genetic Transformation in Escherichia coli. In: Bacterial Transformation and Transfection, Eds. Portoles/Lopez/Esponosa (1976, in press). Elsevier/North-Holland Biomedical Press, Amsterdam, The Netherlands.